Chapter 2: Strategies for Local Governments Chapter 3: Site Assessment and Design for Low Impact Development. Break Out Group 10:30 am to 12 pm

Transcription

1 Chapter 2: Strategies for Local Governments Chapter 3: Site Assessment and Design for Low Impact Development Break Out Group 10:30 am to 12 pm A Low Impact Development Manual for Coastal South Carolina January 9, 2014 Charleston, SC Funded by the National Estuarine Reserve System Science Collaborative

2 Sadie Drescher Watershed Researcher and Planner Center for Watershed Protection, Inc. Blaik Keppler Coastal Training Program Coordinator ACE Basin National Estuarine Research Reserve Michelle LaRocco Coastal Training Program Coordinator North Inlet Winyah Bay National Estuarine Research Reserve Katie Ellis Coastal Training Program Assistant, SCDNR April Turner Coastal Communities Specialist SC Sea Grant Consortium

3 Objectives Understand site design recommendations that will contribute to LID Understand how communities can incorporate the manual recommendations into new or existing policy LID project team record feedback and coordinate feedback input for the manual

4 How to accomplish our objectives today Add productive comments and conversation What changes are needed? How can we improve the content? Specific content, people to contact, etc. Form decision points Make action items and timelines

5 Outline for Today s Work 1. Your feedback Major discussion points Unclear areas, additions needed, deletions needed Beefs 2. Review the manual sections 3. Gather feedback 4. Develop an action plan and timeline

6 This Chapter outlines the current federal, state, and local stormwater regulations. Then, the planning and regulatory strategies needed for coastal SC LID implementation are presented.

7 Chapter 2: Strategies for Local Governments 2.2 Applicable Regulations and Requirements for Stormwater and LID Federal and State Stormwater Regulations Local Regulations and Ordinances 2.3 Planning Strategies Code and Ordinance Checklist Better Site Design Code and Ordinance Worksheet US EPA Water Quality Scorecard Eight Tools of Watershed Protection Audit Coastal Community Watershed Management Checklist

8 Chapter 2: Strategies for Local Governments 2.3 Planning Strategies (continued) Planned Unit Development Planned development districts (PDDs) was codified into SC law (SC ) Allow for flexibility in the development process 2.4 Regulatory Strategies Site Plan Review Tracking, Inspection, and Verification Enforcement

9 Chapter 2: Strategies for Local Governments What changes are needed? How can we improve the content? Specific content, people to contact, etc. Form decision points Make action items and timelines

10 Revisit the Objectives Understand site design recommendations that will contribute to LID Understand how communities can incorporate the manual recommendations into new or existing policy LID project team record feedback and coordinate feedback input for the manual

11 Site assessment and design for LID seeks to create less impervious cover, conserve more natural areas, and use pervious areas more effectively to treat storm water runoff.

12 Chapter 3: Site Assessment and Design for Low Impact Development 3.1 Introduction to Site Assessment and Design Better Site Design Development projects can be planned and designed to reduce their impact on coastal aquatic and terrestrial resources, particularly when an effort is made to protect and conserve natural areas, reduce impervious cover, and integrate stormwater management with site design.

13 Chapter 3: Site Assessment and Design for Low Impact Development 3.2 Conservation Principles for Coastal SC Key conservation principles for coastal SC include conserving land; protecting critical resources, open space, and tree canopies; preserving native vegetation, soils and buffers; reducing impervious cover; and planning for future development. These conservation principles are part of an overall watershed approach to stormwater management. Conservation principles are detailed here and include available science, policy recommendations, and examples.

14 Chapter 3: Site Assessment and Design for Low Impact Development 3.2 Conservation Principles for Coastal SC Land Conservation Prioritize areas, use local data, and assess $ value Local gov t control land development and can fill in state/federal gaps Preserve and Maintain Open Space Critical to maintaining water quality at the regional level Transfer Development Rights & Purchase Development Rights

15 Chapter 3: Site Assessment and Design for Low Impact Development 3.2 Conservation Principles for Coastal SC Protect Forests and Wetlands Wetland loss is a problem SC wetland loss 28% (4.6 million acres) since 1780 (Yarrow, 2009) Wetland role in stormwater SC DNR BMP for Wildlife in Maritime Forest Developments resource

16 Chapter 3: Site Assessment and Design for Low Impact Development 3.2 Conservation Principles for Coastal SC Protect Forests and Wetlands Clemson Extension s Yarrow (2009) provided the following three basic wetland management plan considerations: Inventory, Management Considerations, and Management Goals Resources provided

17 3.2 Conservation Principles for Coastal SC Promote Buffers SC has several buffer guidance documents that provide buffer definitions, examples, case studies, and recommendations. The Final Report of the Shoreline Change Advisory Task Force Adapting to Shoreline Change: A Foundation for Improved Management and Planning in South Carolina called for a 25 foot minimum buffer for new development in the coastal zone, tax incentives for buffers, and more shoreline buffers (SCDHEC-OCRM, 2010); SC Task Force for Forested Riparian Buffers report recommended 100 to 300 foot riparian buffers (SCTFFBR, 2000);

18 3.2 Conservation Principles for Coastal SC (continued) Promote Buffers SCDHEC Vegetated Riparian Buffers and Buffer Ordinances that recommends at least a 50 to 100 foot buffers (SCDHEC-OCRM); SCDHEC Backyard Buffers for the South Carolina Lowcountry provided guidance for buffer implementation and maintenance to homeowners (SCDHEC); and Critical Buffer Ordinance report provided an overview for buffer intent, buffer implementation, and provided case studies in the City of Charleston and the Town of Mount Pleasant (Halfacre-Hitchcock and Hitchcock, no date). SC Construction General Permit requires a 40 foot buffer during construction

19 Chapter 3: Site Assessment and Design for Low Impact Development 3.2 Conservation Principles for Coastal SC Protect Tree Canopy Stormwater and other value Landscape community to promote, maintain, & educate Need SC tree canopy goal example Reduce Impervious Cover Managing IC is critical because increased IC is linked to impacts on water quality, wildlife, and human health through degraded water quality impacts (e.g., bacteria) (Mallin, 2000; Mallin et al., 2001; Holland et al., 2004; Schueler et al., 2009).

20 Chapter 3: Site Assessment and Design for Low Impact Development 3.2 Conservation Principles for Coastal SC Planning for Future Growth Conditions and Patterns More sustainable growth patterns Promote LID, reduce IC, preserve natural areas Conservation, Land Use, and Stormwater Management Incentives Incentives will support the manual s recommended actions Conservation incentive case study Laurel Oak Grove, JI

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22 Chapter 3: Site Assessment and Design for Low Impact Development 3.3 Neighborhood Site Design Considerations for Coastal SC To improve stormwater management use innovative community and subdivision designs that significantly reduce the impact on water quality and required municipal services. LID and Compact Development Upstate Forever and Clemson University found that compact development has half the sediment and nutrients from typical development (Privette, et al. 2011)

23 Chapter 3: Site Assessment and Design for Low Impact Development 3.4 LID Roadway Design Reduce the IC with less wide roads, sidewalks, and streets. Improve stormwater function by allowing flexibility for the materials, design, and promoting stormwater management. Streets constitute 40 to 50% of IC in traditional residential developments Narrower streets can reduce IC by 5 to 20% Common width is 32 to 40 ft Recommended width 18 to 16 ft

24 3.4 LID Roadway Design Street Widths

25 Chapter 3: Site Assessment and Design for Low Impact Development 3.4 LID Roadway Design Right-of-Way Width SC DOT, the ROW refers to the land secured and reserved by the Department for the construction, improvement, and maintenance of the highway (SC DOT 2007). The Institute of Traffic Engineers (ITE) guidelines recommend a minimum ROW width of 50 feet for low density development and 60 feet for medium and highdensity developments (ITE, 1997).

26 Chapter 3: Site Assessment and Design for Low Impact Development 3.4 LID Roadway Design Cul-De-Sacs and Alternate Turnarounds 50 to 60 ft or more in radius often required High pavement results ~11,000 square feet Recommend 30 to 40 ft Small reduction in bulb radius leads to a significant reduction in impervious cover Allow stormwater management Intersection Geometry Minimize size

27 Chapter 3: Site Assessment and Design for Low Impact Development 3.4 LID Roadway Design Curb Requirements How can curb requirements be achieved? What works to reduce curbs and increase stormwater management? Reduce curbs where possible Direct IC to vegetation/lid Sidewalks Reduce width Allow on one side of street Grade to vegetation/lid Direct to vegetation and/or LID Allow alternative materials

28 Chapter 3: Site Assessment and Design for Low Impact Development 3.4 LID Roadway Design Driveways Typical single is 10 to 12 ft wide and double is 18 to 20 ft wide Recommend single < 9 ft wide and double <18 ft Use shared driveway Allow alternative materials Summary Stormwater, watershed, and community benefits for reducing impervious cover and increasing the water runoff management

29 Chapter 3: Site Assessment and Design for Low Impact Development 3.5 LID Parking Guidance Parking is a necessity but parking lots are often designed to be overly large and local codes can be a barrier. This chapter discusses the essential regulatory strategies that emphasize parking efficiency and provides suggestions for reducing impervious cover.

30 Chapter 3: Site Assessment and Design for Low Impact Development 3.5 LID Parking Guidance Alternative Parking Surfaces & Shared Offsite Parking Allow Parking Ratios Base on average daily demand; do not base on projected peak demand Typically based on minimum number of spaces needed to accommodate the highest hourly parking during the peak season at the site Use maximums not minimum requirement See Table 3-15

31 3.5 LID Parking Guidance Based on the findings from the study, the City of Greenville adjusted its parking requirements.

32 LID Parking Lot Case Study: 15 George Street Charleston, SC

33 Chapter 3: Site Assessment and Design for Low Impact Development 3.5 LID Parking Guidance Stall and Aisle Geometry Typical stall is 10 ft wide and 20 ft long Recommend 9 ft wide and 18 ft long

34 Chapter 3: Site Assessment and Design for Low Impact Development 3.5 LID Parking Guidance Parking Lot Landscaping Use landscaping to support stormwater management

35 Chapter 3: Site Assessment and Design for Low Impact Development 3.6 Incorporating LID into Existing Development Developments that occurred with no stormwater management controls or with outdated stormwater management controls, represent an opportunity to capture and treat stormwater runoff. Assessing the site for potential to capture and treat stormwater is an opportunity to provide additional water quality and stream channel protection to the community

36 Chapter 3: Site Assessment and Design for Low Impact Development 3.6 Incorporating LID into Existing Development Retrofitting Structural stormwater management practices that can be used to address existing stormwater management problems in a watershed. Infill Development An excellent opportunity for LID stormwater management. Horry County, SC, has open space advisory boards that are in the process of preparing a plan to promote infill as a prioritization tool (Wood, pers. comm., 2013).

37 Chapter 3: Site Assessment and Design for Low Impact Development 3.7 LID Landscaping Both hardscaping and vegetation choices affect stormwater quantity and quality Soil Preparation: avoid compaction, stockpile topsoil Mulching: use organic material; depth and type dependent on landscape use Vegetation: use natives, reduce lawn cover Maintenance: soil testing, irrigation, pruning, etc.

38 Native Plants are not available Many landscaping contractors are less familiar with planting strategies Some property owners prefer a more manicured appearance Many property owners desire lush green lawn areas and large expanses of turf Vegetative systems require a long-term commitment to maintenance

39 Revisit the Objectives Understand site design recommendations that will contribute to LID Understand how communities can incorporate the manual recommendations into new or existing policy LID project team record feedback and coordinate feedback input for the manual

40 Chapter 3: Site Assessment and Design for Low Impact Development What changes are needed? How can we improve the content? Specific content, people to contact, etc. Form decision points Make action items and timelines

41 Action Items and Timeline 1. Your feedback Major discussion points Unclear areas, additions needed, deletions needed Beefs 2. Review the manual sections 3. Gather feedback 4. Develop an action plan and timeline

42 The End Thanks! Charleston, SC Wadmalaw Island